Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al 2 O 3 /Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

Saadah Ahmad, Shahrir Abdullah and Kamaruzzaman Sopian
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Saadah Ahmad: Faculty of Engineering and Built Environment, National University of Malaysia, Bangi 43600 UKM, Malaysia
Shahrir Abdullah: Faculty of Engineering and Built Environment, National University of Malaysia, Bangi 43600 UKM, Malaysia
Kamaruzzaman Sopian: Solar Energy Research Institute (SERI), National University of Malaysia, Bangi 43600 UKM, Malaysia

Energies, 2020, vol. 13, issue 8, 1-24

Abstract: The simultaneous use of two passive methods (twisted tape and a nanofluid) in a heat transfer system will increase the average Nusselt number ( Nu ) of the system. However, the presence of inserts and nanoparticles inside the tube will create higher pressure drop ( ΔP ) in the system, which can eventually affect the overall enhancement ratio ( η ), especially at higher Reynolds numbers ( Re ). Several modifications of twisted tapes have been made to reduce ΔP , but most showed a decreasing trend of η as Re increased. The objective of this study is to design a new geometry of twisted tape that yields a larger value of Nu and a smaller value of ΔP, which can result in a larger value of η especially at higher Re . A simulation and experimental analysis are conducted in which Re ranges from 4000–16,000 with two types of nanofluids (SiC/Water and Al 2 O 3 /Water) at various values of the volume fraction, ( φ) (1–3%). ANSYS FLUENT software with the RNG k-? turbulent model is adopted for the simulation analysis. Three types of twisted tape are used in the analysis: classic twisted tape with a pitch ratio of 2 (TT PR2), constant-increasing-pitch-ratio twisted tape (TT IPR) and constant-decreasing-pitch-ratio twisted tape (TT DPR). The use of TT IPR generates a stronger swirling flow at the inlet of the tube and smaller ?P , especially near the outlet region. The highest value of η is obtained for 3% SiC/Water nanofluid that is flowing through a smooth circular tube with TT IPR inserts at Re of 10,000.

Keywords: twisted tape; inserts; nanofluid; heat transfer; thermal performance (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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